This invention concerns a method of optimally controlling the furnace pressure of a heating furnace. This invention relates to a method of controlling the atmosphere in a heating furnace and, particularly, a method of suppressing increase of an oxygen concentration in the atmosphere. This invention relates to an operation method of a heating furnace having heat regenerating burners and a heating furnace, particularly, to an operation method for conducting alternate combustion of paired burners in heat regenerating burners advantageously and a heating furnace used directly for the operation. This invention concerns a method of measuring the concentration of an atmospheric gas in a heating furnace and a heating furnace.
A heating furnace for steel materials is used with an aim of re-heating steel pieces roughly rolled in a blooming factory or continuously rolling cast pieces into final products to a predetermined temperature suitable to rolling. The heating furnace is generally classified into a batch type and continuous type. Since they have respective advantages and drawbacks, they are used selectively depending on the purposes. Since the continuous heating furnace is suitable to mass production in recent years, they have been often been used, for example, in iron making plants.
FIG. 1 shows a typical example of a cross sectional view for a continuous heating furnace. It generally comprises a preheating zone 1, a heating zone 2 and a soaking zone 3 successively from the side of charging steel materials. At least the heating zone 2 and the soaking zone 3 are heated to and kept at a predetermined temperature by burners 4. Steel material 5 introduced from a charging door 1a into the preheating zone 1 are moved on a transportation path 6 and heated to a predetermined temperature by way of the heating zone 2 and the soaking zone 3 and then delivered to the outside of the furnace from an extraction door 3a on the exit side of the soaking zone 3. Exhaust gases formed by combustion of the burners 4 are discharged from a stack 7 disposed on the entrance of the preheating zone 1 to the outside of the furnace. 7a denotes a recuperator for heat exchange of the sensible heat of an exhaust gas in the stack 7 to the sensible heat of a burner combustion gas and 7b denotes a damper for furnace pressure control. Then, in the continuous heating furnace, it is necessary to heat the steel materials to a temperature suitable to a subsequent rolling step. When the temperature of the steel materials heated in the continuous heating furnace is lower than the lower limit of a predetermined temperature suitable to rolling, it results in undesired effects on the rolling operation and product quality. On the other hand, when the temperature of the steel materials extracted from the heating furnace is unnecessarily higher, heat loss increases in the continuous steel material heating furnace. Therefore, it is important in the continuous heating furnace to heat the steel materials up to the temperature suitable to rolling with necessary minimum of fuels. Further, in the heating furnace, it is also required to control the heating time such that heated steel materials are supplied successively from the heating furnace corresponding to the rolling pitch in the rolling step.
In the continuous heating furnace, heat loss, particularly, radiation energy loss from the heating zone is large. The heat loss is suppressed by providing a preheating zone and a soaking zone at the inlet and the exit of the heating zone to partition the inside of the furnace into three parts.
Steel materials to be charged in the continuous heating furnace includes, for example, cast pieces cooled to a normal temperature and hot charged materials sent directly after continuous casting to the rolling step, and the temperature on the inlet of the heating furnace is various. The heating temperature is varied and the processing amount of steel materials to be heated in the heating furnace also varies. The temperature in the heating furnace has to be controlled in according with such various conditions. The heating temperature is adjusted by increasing or decreasing the combustion amount of burners. The pressure in the furnace fluctuates in this case depending on the change of the combustion amount of the burners.
When the pressure in the furnace is lowered compared with the pressure outside the furnace, external air intrudes into the furnace through the charging door and the extraction door as openings of the heating furnace. When air intrudes into the furnace, since the temperature in the furnace lowers, the combustion amount of the burners is increased. This increases the fuel consumption ratio to increase the cost. When air intrudes into the furnace, since concentration of oxygen in the furnace atmosphere increases, oxidation, nitridation or decarbonization on the surface of steel materials charged in the furnace are promoted. As a result, it results in deteriorates the surface quality of the steel materials.
Accordingly, it is necessary to properly control the pressure in the heating furnace. Various proposals have been made for the control of the furnace pressure. For example, JP-A-61-119987 discloses prevention of air intrusion from a charging door and an extraction door by controlling the furnace pressure set in the soaking zone of a heating furnace to a positive pressure relative to the pressure outside of the furnace (hereinafter simply referred to as positive pressure) in accordance with the amount of exhaust gases generated in the furnace. According to this method, it is possible to control the furnace pressure in an upper region of the furnace with the transportation path as a boundary (hereinafter referred to as an upper zone) to a positive pressure. However, when the combustion load on the entire heating furnace is small, the furnace pressure in the lower region of the furnace with the transportation path as the boundary (hereinafter referred to as a lower zone) becomes negative relative to the pressure outside the furnace (hereinafter referred to as a negative pressure). It has been difficult to reliably prevent intrusion of air through gaps below the charging door and the extraction door. It has been difficult to reliably prevent intrusion of air through so-called extra fork openings in which the doors are closed while being engaged to each other in a comb teeth shape. Comb-shaped extract fork opening is shown at 3C in FIG. 14.
Further, JP-A-9-209032 discloses optimum control for a furnace pressure in accordance with the amount of combustion load on a heating furnace by a furnace pressure damper disposed in a stack through which exhaust gases from the heating furnace are passed in the upper region of the soaking zone. However, when the amount combustion load is small, draft in the stack increases compared with the pressure loss due to the flow of exhaust gases from the inside of the furnace to the stack. The draft means that gases heated in the stack or in the furnace cause buoyancy to form a negative pressure. In this case, it is difficult to form a positive pressure as far as the lower zone by the furnace pressure damper. It has been difficult to reliably prevent intrusion of air from the charging door and the extraction door.
JP-A-7-316645 discloses a method of connecting a gas supply pipeline system to a stack on the exit of a recuperator and blowing a gas such as air into the stack thereby controlling the furnace pressure. This method requires to additionally provide a blower, various pipelines and a control system for controlling the furnace pressure. It involves a problem in that the installation cost is high and the maintenance is troublesome. In addition, since ducts or accessory equipments are incorporated in a complicate manner at the periphery of the heating furnace, there is no room for installation space and additional prevision of the control system is difficult.
Prevention of air intrusion into the heating furnace is extremely important in view of the product quality and in view of the operation of the heating furnace. Various techniques have been proposed. For example, JP-A-11-172326 proposes to jet out a combustible gas from a nozzle disposed near an extraction port separately from heating burners in a furnace and consume oxygen in intruding air upon combustion.
However, it requires provision of an exclusive combustion gas jetting nozzle near the extraction port to increase an installation cost. Further, while this is effective for intrusion air from a portion above the position where the jetting nozzle is disposed but the effect is insufficient for intrusion air from a portion below the position where the jetting nozzle is disposed. Since the furnace pressure is negative in the lower portion, intrusion of air to the portion is inevitable. Among all, it has been difficult to reliably prevent intrusion of air through the extraction fork opening.
In recent years, in a continuous heating furnace, operation for a heating furnace with less heat loss has been conducted by using heat regenerating burners as the heat source and re-utilizing heat in exhaust gases for preheating of burner combustion air. FIG. 2A and FIG. 2B show an example for the structure of a heat regenerating burner. As shown in the Example of FIG. 2A and FIG. 2B, a heat regenerating burner comprises a pair of burners 40a and 40b opposed to each other between both side walls of a heating furnace soaking body 3, both-way channels 41a and 41b used for introducing combustion air from the outside of the furnace to each of the burners and for introducing exhaust gases from the inside of the furnace by way of each burner to the outside of the furnace, and heat regeneration bodies 42a and 42b disposed to the openings in each of the channels on the side of the burners in the illustrated example. In the heat regenerating burner, the paired burners are alternately put to combustion. For example, as shown in FIG. 2A, when combustion air is supplied to the burner 40a from the both-way channel 41a and fuel 43a is supplied to burn the burner 40a, an exhaust gas in the furnace is sucked from the burner 41 opposed thereto, the exhaust gas is passed through the heat regeneration body 42b to recover the heat and then introduced to the both-way channel 41b and discharged out of the furnace.
Then, the burner combustion operation is switched and, when a switching valve 44 for the both-way channels 41a and 41b is switched to change the connection with conduits for air and exhaust gas described above and then, as shown in FIG. 2B, a combustion air is supplied to the burner 40b from the both-way channel 41b by way of the heat regeneration body 42b, it is supplied while pre-heating the combustion air by utilizing the heat recovered in the heat regeneration body 42b in the step previously shown in FIG. 2A and, simultaneously, fuel 43b is supplied to burn the burner 40b. At the same time, an exhaust gas in the furnace is sucked from the burner 40a opposed thereto and the exhaust gas is passed through the heat regeneration body 42a to recover the heat and then introduced to the both-way channel 41a and discharged out of the furnace.
Operation for the heating furnace with less heat loss can be conducted by repeating the alternate combustion of the burners shown in FIG. 2A and FIG. 2B described above, for example, on every several tens seconds.
In this case, for the suction of the exhaust gas from the burner in a not combustion state, a suction device 8, for example, a suction blower is disposed to the end of a path 45 for sucking by way of the heat regeneration body 42b or 42b from the burner 40a or 40b, for example, as shown in FIGS. 2A and 2B, and the exhaust gas from the burners is sucked by driving the suction device 8.
By the way, in the operation of the heating furnace using the heat regenerating burners described above, during the period from the start of the burner combustion till the set temperature, or in a case of controlling the atmosphere in the furnace to a lower temperature region such as at about 800xc2x0 C., the temperature of the exhaust gas sucked from the burner and passed through the regeneration body also lowers. As a result, moistures or sulfur contents contained in the exhaust gas are condensed at the exit of the exhaust gas of the regeneration body or in the path 45 succeeding thereto. Liquids caused by condensation, so called drains may sometimes stagnate at the exit of the exhaust gas of the regeneration body. When the burner combustion operation is switched as it is into a combustion state, since drains are mixed with the combustion air, this results in a problem of lowering the temperature of the combustion flame. Lowering of the temperature for the combustion flame by the drains lowers the heat efficiency of the heating furnace and may sometimes bring about a trouble in the low temperature operation.
Further, in a heating furnace where plural heat regenerating burners are disposed, the path introducing the exhaust gas rendered to a low temperature from the burner through the heat regeneration body to the suction device is long. Drains are formed not only at the exit of the heat regeneration body but also in the course of the path. Then, drains formed on the path cause corrosion to the impeller of the suction device. When solid components contained in the drains damage the impeller by abrasion, it may cause a worry of developing to fatal accidents. Accordingly, in the heating furnace having the heat regenerating burners, the suction device for the exhaust gas has been checked frequently. Further, it has also brought about a problem for the increase of the cost requiring for frequent maintenance such as exchange of the impeller of the suction device.
In view of the problems regarding the drains described above, JP-A-10-30812 discloses a device shown in FIG. 3. An exhaust gas in a heating furnace (for example, in soaking zone 3) is flowed through a bypass pipe 51 to an exhaust gas pipeline channel 50 separately from a channel of discharge through a burner 40a and an exhaust gas pipeline channel 50 to the outside of the furnace. It is disclosed that the temperature of the exhaust gas pipeline channel 50 is kept above a dew point of the exhaust gas with this constitution.
However, in a case of heating at a relatively low temperature for a long time in order to make the temperature uniform along the direction of the thickness of the steel material or in a case where installation troubles occur and high load combustion is impossible, it is necessary to burn the burners at an extremely low load. In this case, since the suction device (blower) is operated while reducing the suction power thereof to less than about 10% thereof, operation of the suction device sometimes becomes unstable. Swirling stream can not be obtained stably on the entire surface to result in a portion where swirling stream can not be obtained by stalling. Then, this not only brings about a difficulty in keeping the suction amount of the exhaust gas from the burner constant but also results in generation of abnormal vibrations to the blade to possibly damage the blower depending on the case.
As has been described above, while the technique described in JP-A-10-30812 can solve various problems regarding the drains in a case of combustion at low load, it can not still solve the problem that the operation of the suction device becomes unstable. Further, since control valves are present respectively to the exhaust gas 50 and the bypath pipeline 51 described in the publication, this also results in a problem that the control therefor is complicated.
For keeping the surface of the steel materials during heating satisfactory, it is important to strictly control the atmosphere in the furnace of the continuous heating furnace. For example, when the oxygen concentration in the furnace atmosphere increases, surface oxidation, nitridation or carburization of materials to be heated such as steel materials charged in the furnace are promoted and, when they are rolled as they are, the surface quality of the products is deteriorated. For improving or keeping the product quality, it is necessary to suppress increase for the oxygen concentration in the furnace atmosphere. For this purpose, it is important to exactly measure the oxygen concentration in the furnace atmosphere.
In addition to the oxygen concentration, it is also important to exactly measure the temperature for nitrogen, carbon monoxide or oxynitrides in the furnace atmosphere. Nitrogen gives an effect on nitridation on the surface of the steel materials, carbon monoxide can be utilized for the detection of incomplete combustion of burners and oxynitrides are necessary for the administration of environmental discharge standard values.
Then, JP-A-62-40312 discloses that each of the probes for measuring the oxygen concentration and the Co concentration in the heating furnace is made moveable, concentration is measured at plural measuring positions and an average concentration value is determined to amend and control the air ratio in the burners.
However, since it is necessary to additionally dispose a driving system or control system for measuring the density, the installation cost is high. Further, there is also a problem that the maintenance is complicate and since ducts or auxiliary equipments are incorporated complicatedly in the heating furnace, there is no room for disposition and it was often difficult to additionally dispose a driving system or control system.
Further, JP-A-9-53120 discloses a heating furnace in which a partition wall is located inside of the furnace wall of the heating furnace on the extraction side and below the skid along the lateral direction of the furnace, and an oxygen densitometer and an exhaust pipe for discharging the atmospheric gas to the outside of the furnace are disposed between the partition wall and the furnace wall on the extraction side. It is disclosed that flow rate in the exhaust pipe is controlled while measuring the oxygen density by using the oxygen densitometer in the heating furnace.
However, for conducting measurement by the oxygen densitometer between the partition wall and the furnace wall on the extraction side, a probe has to be inserted from the hearth or furnace wall. When the probe is inserted from the hearth, since probe is damaged or clogged due to dropping and deposition of scales, it is difficult to measure the density at high reliability for a long period of time. Further, when the probe is inserted from the furnace wall, since the probe is exposed to high temperature region in the furnace and distorted, it may cause a worry that the measuring point is displaced or the probe is damaged.
One of the objects of this invention is to provide a method of controlling a furnace pressure capable of reliably preventing air from intruding into a heating furnace.
The present inventors have made an earnest study on the intrusion of air in a case where the pressure in the furnace becomes negative. Air intrudes from both of the charging door and the extraction door into the furnace. As shown in FIG. 1, a stack 7 is disposed just after the charging door 1a. Air intruding from the charging door 1a directly passes to the stack 7 and discharged out of the furnace. It has been found that air intruding through the charging door 1a less causes a factor of bringing about increase of the oxygen density in the furnace or lowering the temperature in the furnace. It is important to avoid the intrusion of the air from the extraction door in order to avoid increase of the oxygen concentration in the furnace or lowering of the temperature in the furnace. For this purpose, it has been found that it is important to properly control the furnace pressure in the soaking zone to which the extraction door is disposed.
As described above, it is difficult to maintain the pressure of the furnace positive in a lower region below the transportation path of the soaking zone upon control of the furnace pressure by on/off of the damper disposed in the stack, particularly, in a case where the combustion load is small. This is because the amount of the exhaust gas generated is decreased and the pressure loss of the exhaust gas from the inside of the furnace to the passage through the stack is decreased, whereas the draft increases more to the downstream in the furnace. The distribution of the furnace pressure lowers gradually toward the downstream of the heating furnace relatively. In the downstream region, draft increases compared with the pressure loss of the exhaust gas tending to cause a negative pressure.
By the way, operation of a heating furnace with less heat loss is adopted by using heat regenerating burners as a heat source of a continuous heating furnace and re-utilizing the heat in the exhaust gas for preheating combustion air of burners. It has been studied on the furnace pressure control in a heating furnace using the heat regenerating burners. It has been found that a strict furnace pressure control is possible, particularly, in a case of using heat regenerating burners as a heat source in the lower region of the soaking zone, by utilizing the mechanism characteristic to the heat regenerating burner and this invention has thus been completed.
That is, this invention provide a method of controlling a furnace pressure in a heating furnace using heat regenerating burners, in which a suction ratio of an exhaust gas from the burner to a heat regenerating body is adjusted in accordance with the combustion load on the entire heating furnace, thereby controlling the furnace pressure in a soaking zone.
Further, when the present inventors have made an earnest study on a method capable of maintaining the furnace pressure positive in a lower region of the transpiration path in a soaking zone even in a case where the combustion load is small, it has been found that dilution air supplied to the inlet of a recuperator disposed to a stack can be utilized for the control of the furnace pressure with an aim of protecting the recuperator disposed in the stack.
That is, this invention provides a method of controlling a pressure in a heating furnace of disposing a recuperator in the midway of a stack for introducing an exhaust gas in the heating furnace to the outside of the furnace, preheating combustion air supplied to burners as a heat source of the heating furnace by the recuperator, and supplying dilution air to the stack at an inlet of the recuperator for protecting the recuperator against high temperature atmosphere, characterized by controlling the flow rate of the dilution air in accordance with the temperature of the exhaust gas on the inlet of the recuperator and the combustion load of the heating furnace, thereby controlling the furnace pressure.
An object of this invention is to provide a method capable of reliably preventing intrusion of air from an extraction door into a heating furnace. Further, an object of this invention is to provide a heating furnace used for the method.
When the present inventors have made an earnest study on the intrusion of air in a case where the pressure in the furnace becomes negative, it has been found that although air intrudes into the furnace from both of the charging door and the extraction door, since the stack 7 is disposed just after the charging door 1a as shown in FIG. 1, air intruding through the charging door 1a is directly passed to the stack 7 and discharged out of the furnace, it less causes a factor of increasing the oxygen temperature in the furnace or lowering of the temperature in the furnace. Accordingly, it has been found that it is important to avoid intrusion of air from the extraction port in order to avoid increase of the concentration of the oxygen in the furnace or lowering of the temperature in the furnace and, for this purpose, it is important to reliably shut intruding air at the extraction end.
An object of this invention is to provide an operation method for a heating furnace of not making the operation of an exhaust suction device unstable even in a case where combustion load on heat regenerating burners is small. Further an object of this invention is to provide a heating furnace used for the operation method for the heating furnace.
When the present inventors have made an earnest study on a method of increasing the operation load of a suction device in a case where the combustion load of the heat regenerating burners is decreased and the suction device of the exhaust gas is obliged to be operated at a load of less than 10%, it has been found that it is extremely advantageous to introduce an exhaust gas from the stack that introduces the exhaust gas of the heating furnace to the outsides of the furnace into the suction device to accomplish this invention. An object of this invention is to provide a method capable of exactly measuring the concentration of ingredient gas of the atmosphere in the heating furnace by utilizing an existent facility. A further object of this invention is to provide a heating furnace capable of measuring concentration of ingredient gas of the atmosphere in the heating furnace.
In the operation for the heating furnace using the heat regenerating burners, an operation for heating furnace with less heat loss can be realized by conducting heating repeating the steps shown in FIG. 2A and FIG. 2B, for example, on every several tens seconds.
In the operation for the heating furnace using the heat regenerating burners described above, since suction for the exhaust gas from the heat regenerating burners is conducted at a high speed, the exhaust gases distributed in the lateral direction of furnace are sucked for a wide range. Taking notice on phenomenon, the present inventors have found that the ingredient concentration of the furnace atmosphere can be measured exactly by measuring the ingredient concentration for the exhaust gas sucked from the heat regenerating burner since the exhaust gas in the furnace sucked from the heat regenerating burner favorably reproduces the furnace atmosphere, to accomplish this invention.
The gist of this invention is as described below.
1. A method of controlling a furnace pressure by utilizing heat regenerating burners in a heating furnace having a preheating zone, a heating zone and a soaking zone, in which plural sets of heat regenerating burners each having a pair of burners each having a heat regeneration body and opposed to each other are disposed as a heat source for the soaking zone, wherein the method comprises alternately burning the burners of each pairs of the heat regenerating burners, sucking an exhaust gas in the furnace from the burners during not combustion state, introducing the exhaust gas to the heat regeneration body thereby recovering the heat in the exhaust gas to the heat regeneration body, and utilizing the recovered heat for the heating of combustion air of the burners upon combustion state, thereby conducting operation for the heating furnace, wherein the suction ratio of the exhaust gas from the burner to the heat regeneration body is controlled in accordance with the combustion load on the entire heating furnace to control the furnace pressure in the soaking zone.
2. A method of controlling a furnace pressure in a heating furnace in which a recuperator is located in the midway of a stack for introducing an exhaust gas in the heating furnace to the outside of the furnace and combustion air supplied to burners as a heat source for the heating furnace is preheated by the recuperator, and dilution air is supplied to stack at an inlet of the recuperator for protecting the recuperator against high temperature atmosphere, wherein the flow rate of the dilution air is controlled in accordance with the temperature of the exhaust gas on the inlet of the recuperator and combustion load on the heating furnace, thereby controlling the furnace pressure.
3. A method of controlling an atmosphere in a heating furnace, comprising independently controlling combustion of heating burners located in a lower region of a furnace extraction end among plural heating burners located in the heating furnace upon opening the extraction door of heating furnace, extending the flame of the burners for the width of the opening in the lateral direction of extraction port, and shutting the intruding path of air from the extraction port with the burner flame, thereby suppressing increase of the oxygen concentration in the furnace.
4. A method of controlling an atmosphere in the heating furnace as defined in 3, wherein a partition wall standing vertically from the hearth is disposed to the heating burner located at the extraction end of the furnace on the inner side of the furnace thereby forming an ascending stream along with the partition wall, and carrying air intruding from the extraction port on the ascending stream.
5. A method of controlling an atmosphere in the heating furnace as defined in 3 or 4, wherein combustion operation is conducted under a low air ratio of the heating burners disposed at the extraction end of the furnace.
6. An operation method for a heating furnace having a heat regenerating burner in which a pair of burners each attached with a heat regeneration body and opposed to each other are disposed as a heat source, the method comprising alternately burning each pair of burners in the heat regenerating burner, sucking an exhaust gas in the furnace from the burners during not combustion state, introducing the exhaust gas to the heat regeneration body thereby recovering heat in the exhaust gas to the heat regeneration body, and utilizing the recovered heat for heating the combustion air of the burners during combustion state, thereby conducting operation for the heating furnace, wherein a hot blow is supplied to a suction device for sucking the exhaust gas in the furnace from the burner in the not-combustion state through the heat regeneration body in a case where the combustion load on the heat regenerating burner is small.
7. An operation method for a heating furnace as defined in 6, wherein the hot blow is the exhaust gas in the stack for introducing the exhaust gas in the heating furnace to the outside of the furnace.
8. A method of measuring the concentration of an atmosphere gas in a heating furnace comprising heat regenerating burners in which a pair of burners each attached with a heat regeneration body are opposed to each other as a heat source, by alternately burning each pair of burners of the heat regenerating burner, sucking an exhaust gas in the furnace from the burners during not-combustion state, introducing the exhaust gas to the heat regeneration body thereby recovering the heat in the exhaust gas to the heat regeneration body, and utilizing the recovered heat for heating the combustion air of the burners during combustion state, thereby conducting operation for the heating furnace wherein a portion of the exhaust gas sucked from the burners is introduced into an analyzer and measuring the concentration of ingredients in the exhaust gas.
9. A method of measuring the concentration of the atmosphere gas in the heating furnace as defined in 8, wherein the measured value for the ingredient concentration of the exhaust gas sucked from the heat regenerating burners is used as a typical value for the ingredient concentrations in the zone of the heating furnace in which the heat regenerating burners are disposed.
10. A heating furnace having plural heat regenerating burners in which a pair of burners each attached with a heat regeneration body are opposed to each other as a heat source, and adapted for alternately burning each pair of burners in the heat regenerating burners, sucking an exhaust gas in the furnace from the burners during not combustion state, introducing the exhaust gas to the heat regeneration body thereby recovering heat in the exhaust gas to the heat regeneration body, utilizing the recovered heat for heating the combustion air of the burners during combustion state thereby conducting operation, wherein at least the heat regenerating burners located in the lower region at the extraction end of the heating furnace have a combustion control system independent of other heat regenerating burners.
11. A heating furnace as defined in 10, wherein a partition wall standing from the hearth is located at a position for putting the heat regenerating burner having an independent combustion control system relative to the extraction door of the heating furnace.
12. A heating furnace having heat regenerating burners in which a pair of burners each attached with a heat regeneration body are opposed to each other as a heat source, and adapted for alternately burning each pair of burners in the heat regenerating burners, sucking an exhaust gas in the furnace from the burners during not combustion state, introducing the exhaust gas to the heat regeneration body thereby recovering heat in the exhaust gas to the heat regeneration body, utilizing the recovered heat for heating the combustion air of the burners during combustion state thereby conducting operation, a suction device is disposed at the end of the path for sucking the exhaust gas in the heating furnace from the burners during not-combustion state by way of the heat regeneration body, and a pipeline channel is disposed to the sucking path on the inlet side of the sucking device for introducing a hot blow by way of an ON/OFF valve to the suction device.
13. A heating furnace as defined in 12, wherein the pipeline channel is connected with a stack for introducing the exhaust gas in the heating furnace to the outside of the furnace and introducing the exhaust gas in the heating furnace as a hot blow.
14. A heating furnace as defined in 12 or 13, wherein a recuperator is disposed to the upstream of the pipeline channel in the stack.
15. A heating furnace having plural heat regenerating burners in which a pair of burners each attached with a heat regeneration body are opposed to each other as a heat source, and adapted for alternately burning each pair of burners in the heat regenerating burners, sucking an exhaust gas in the furnace from the burners during not combustion state, introducing the exhaust gas to the heat regeneration body thereby recovering heat in the exhaust gas to the heat regeneration body and utilizing the recovered heat for heating the combustion air of the burners during combustion state thereby conducting operation, wherein a probe for sampling a portion of the exhaust gas and an analyzer for measuring the concentration of ingredients of the sampled exhaust gas are disposed in the midway of the path for discharging the exhaust gas in the heating furnace from the burner during not-combustion state by way of the heat regeneration body.